Extremely poor service

I bought a phone on contract from them, within the first month the phone was giving me problems and it was faulty. I called I smart and they sent a courier to collect the phone from my house. I was told that the phone will be in for repairs for 21 days. during that time I was not given a replacement phone to use while the phone was in for repairs. I was forced to buy another phone to use in the meantime. Then the brought the phone back to me and again the phone continued giving me problems. It was not switching on and when I told them that the battery could be faulty, they asked how long did i charge my phone. I told them that the phone was on the charger overnight and their excuse was I should not have charged the phone overnight and that is why it was faulty